, (, ) .
, .
: 125 ( 8 ) 8- . , , 64 /; (), . 128 /. , , , 32 , 2048 /. , .
, () , .
ISDN (Integrated Services Digital Network), .
, , , , . , ISDN , , - . ISDN $600-800. , ISDN, . , ISDN- .
(DSL, Digital Subscriber Line). , , xDLS- , (), , .
1990 Bellcore HDSL (High Bit Rate DSL), ISDN. HDLS - , . 768 1024 / ( 1 1) 3,6 . 1,544 2,048 /.
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HDSL:
SDSL (Symmetric DSL) HDSL, ;
RADSL (Rate Adaptive DSL) ( 8) ;
MSDSL (Multirate SDSL) 64 1152 / ;
ADSL (Asymmetric DSL) , .
. 8 /; 1,5 /. , (, V.92 ). ADSL-, , () : (downstream), (upstream) . ( ) .
1997 ADSL Universal ADSL (UADSL), , , :
3,5 1,5 /, 384 /;
5,5 ( ) 640 /, 196 /.
ADSL (), , UADSL . , ().
, , VDSL (Very high-speed DSL) , :
300 52 /, 2,3 /;
1,5 13 /, 1,6 /.
, VDSL , SDSL. , VDSL.
ISDN ADSL - SDH (Synchronous Digital Hierarchy). SDH : 155,52 / (STM-1), 622,08 / (STM-4) 2488,32 / (STM -16) 10 000 / (STM-64), . SDH , , .
4: